Preheat the oven to 375 degrees. Meanwhile, cook the turkey sausage (with casings removed) over medium heat for 7-8 minutes until cooked through, crumbling the sausage as it cooks. Drain if necessary.
In a 2½ or 3 quart greased casserole dish, spread ¼ cup of the sauce in the bottom. Next, layer ⅓ of the cheese ravioli, ⅓ of the sausage, and ⅓ of the cheese. Pour ⅓ of the remaining sauce over the top. Repeat the layers two more times. Sprinkle the parmesan cheese evenly over the top.
Cover and bake for 25-30 minutes. Uncover and bake for another 10 minutes until the top is lightly browned
The ravioli does not need to be defrosted before assembling and baking the casserole.